Technical Support - MDM
56/104
599 77 39-16 Rev. 00
11.12
Solenoid valves
11.12.1 General characteristics
This component introduces water into the detergent dispenser and is controlled electrically by the main circuit
board via TRIAC. The level of water in the tub is controlled by the analogue pressure switch.
1. Water inlet
2. Solenoid valve body
3. Filter or needle trap
4. Flow reducer
5. Coil
6. Spring
7. Moving core
8. Rubber
9. Membrane
10. Water outlet
11.12.2 Operating principle
When idle, the core, pushed by a spring, keeps the central hole of the membrane closed and so the latter
hermetically seals access to the water inlet duct.
When the coil is powered, the core is attracted, releasing the central hole of the membrane. Consequently
the valve opens.
Diagram with universal Motor Diagram with Inverter
1. Main electronic circuit boar
2. Door safety interlock
5. Pre-wash solenoid valve
6. Wash solenoid valve
11.12.3 Mechanical jamming of the solenoid valve
The solenoid valve may jam open without being actuated (which will cause flooding if the pressure switch
controlling the water level does not trip). If this occurs, the electronic control system (which continuously
monitors the flow sensor) will lock the door, start the drain pump and display an ALARM simultaneously.
11.12.4 Low water pressure
If the flow sensor does not generate a signal during the water fill phases, even though power is being supplied
to the solenoid valve, the cause of this condition may be a closed water tap or clogged filter on the solenoid
valve (with ensuing low water pressure). If this occurs, only a WARNING will be displayed and the cycle will
continue for five minutes, after which time an ALARM will be signalled.
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